AuthorTopic: Transition from Zen to Plusnet (Read 1040 times)

I was happy with the performance of my line, and thought it would largely stay the same (I use Plusnet at work and have been happy with them as well).

However after the switch I have had some very erratic performance (please see broadband quality links below), this increase increase in jitter and latency was also accompanied with the loss of approx 10mbs of bandwidth. The router and modem used is the same for both Zen and Plusnet.

I spoke to Plusnet support and they indicated that there was a 10 day training period, and that I should wait for the line to stabilise.

I was just wondering if its normal to have this sort of instability when changing ISP's, when the line has been stable on the previous ISP?

And is it something to be concerned about or will it hopefully resolve itself?

Whilst you were with Zen, the DLM (Dynamic Line Management) settings for your line would have had time to enable/disable VDSL features to give you the fastest, most stable service your line could physically support.

When you change supplier, these settings are reset, so DLM needs to re-learn about your line.

At the moment, your line will be running without any bells and whistles enabled to combat interference or suboptimal line conditions.

In particular, a feature called G.INP, designed to limit the impact of crosstalkers (other VDSL users' signals), will currently be switched off.

Over the next week or so, DLM will start enabling features (G.INP, Interleaving) to increase your line's stability. It may also start lowering the SNRM (signal-to-noise ratio margin) if your line reaches a level of stability that'll support faster speeds.

As you're using the same modem as before, there's no reason why DLM won't eventually bring you back to the rates you were seeing before.

It's a shame the settings cannot be transferred between ISPs, forcing the line to be retrained every time you switch ISP is a disincentive to switch ISPs.

To be fair, most users would almost certainly change their router/modem when changing providers, so having DLM reset during a provider swap is probably the safest way of reconfiguring the line based on the performance of the new equipment.

Anecdotally, DLM's quicker at finding the stable config when starting from scratch. It seems much slower at deciding to undo existing restrictions.

From my own example, I switched from BT to Vodafone, swapping my Openreach HG612 with the Vodafone-supplied router. DLM quickly (~4 days) noticed that the Vodafone router was a piece of junk and banded my 58 meg line down to 34. Eventually VF relented and gave me the details I needed so I could switch back to the Openreach modem. That ran for another couple of weeks without DLM removing the limit. Eventually VF got an engineer out who requested the DLM reset and I was back to normal.

I don't think ~1 week of training every 12, 18 or 24 months is much of a disincentive to switching. What's really a disincentive is providers not allowing customers to use their own 'known-good' equipment.

(luckily, VF relented a few months after my issue and now generally allow the use of non-VF modems/routers)

Whilst you were with Zen, the DLM (Dynamic Line Management) settings for your line would have had time to enable/disable VDSL features to give you the fastest, most stable service your line could physically support.

When you change supplier, these settings are reset, so DLM needs to re-learn about your line.

At the moment, your line will be running without any bells and whistles enabled to combat interference or suboptimal line conditions.

In particular, a feature called G.INP, designed to limit the impact of crosstalkers (other VDSL users' signals), will currently be switched off.

Over the next week or so, DLM will start enabling features (G.INP, Interleaving) to increase your line's stability. It may also start lowering the SNRM (signal-to-noise ratio margin) if your line reaches a level of stability that'll support faster speeds.

As you're using the same modem as before, there's no reason why DLM won't eventually bring you back to the rates you were seeing before.

Only if the gaining provider uses a Different DLM stability profile, or a change of product or product speed, ie a move from BT WBMC to GEA or 40/10 to 80/20 or vice versa